Yersinia enterocolitica ClpB affects levels of invasin and motility

Expression of the Yersinia enterocolitica inv gene is dependent on growth p hase and temperature. inv is maximally expressed at 23 degrees C in late-ex ponential- to early-stationary-phase cultures. We previously reported the i solation of a Y. enterocolitica mutant (JB1A8v) that shows a decrease in in vasin levels yet is hypermotile when grown at 23 degrees C. JB1A8v has a tr ansposon insertion within uvrC. Described here is the isolation and charact erization of a clone that suppresses these mutant phenotypes of the uvrC mu tant JB1A8v. This suppressing clone encodes ClpB (a Clp ATPase homologue). The I: enterocolitica ClpB homologue is 30 to 40% identical to the ClpB pro teins from various bacteria but is 80% identical to one of the two ClpB hom ologues of Yersinia pestis. A clpB::TnMax2 insertion mutant (JB69Qv) was co nstructed and determined to be deficient in invasin production and nonmotil e when grown at 23 degrees C. Analysis of inv and fleB (flagellin gene) tra nscript levels in JB69Qv suggested that ClpB has both transcriptional and p osttranscriptional effects. In contrast, a clpB null mutant, BY1v, had no e ffect on invasin levels or motility, A model accounting for these observati ons is presented.